Orchard heating system

ABSTRACT

A thermostat, located in an orchard, automatically opens a liquid fuel line, causing the pressure in the line to close contacts in a switch which completes an electric circuit for energizing a resistance element in an orchard heater to ignite the heater.

mted States Patent 11 1 1111 3,718,421 McMechan 1451 Feb. 27, 1973 54] ORCHARD HEATING SYSTEM 1,926,394 9/1933 McCabe ..431/23 [76] Inventor: Maurice H. McMechan, Route 7, POl Box 59, Yakima, wash. 98903 [22] Filed: March 30, 1970 Primary ExaminerWilliam E. Wayner [2]] App] N o 23 635 Attorney-Seed, Berry, Dowrey & Cross [57] ABSTRACT [521 US Cl. ..431/23, 431/74, 431/89,

, 126/595 A thermostat, located 1n an orchard, automatlcally 51 Int. Cl ..F23n 5/24 Opens a liquid fuel line, causing the Pressure in the 53 Field of h. 12 59 5; 431 23 72 39 25 line to close contacts in a switch which completes an 237 2 electric circuit for energizing a resistance element in an orchard heater to ignite the heater. [56] References Cited UNITED STATES PATENTS 14 Claims, 16 Drawing Figures 1,884,256 10/1932 Rogers-etal ..431/23 x PATENTEI] E82 7 I573 SHEET 1 OF 5 PATENTEU 3,718,421

SHEET 2 OF 5 PATENTED m2? ms SHEET 5 OF 5 use H ORCHARD HEATING SYSTEM BACKGROUND OF THE INVENTION This invention concerns heaters used periodically in orchards or the like during cold weather conditions to prevent frost damage to the crop, and more particularly concerns an improved system for automatically igniting such heaters.

Historically orchards. have been heated during cold weather conditions by placing about fifty heaters per acre around the orchard, filling them with fuel, and when the weather conditions indicated the need for heat in the orchard manually lighting each heater. A typical heater of this type is known as a smudge pot and comprises a container which is adapted to store a gallon or more of liquid fuel in its lower portion and has an opening in its upper end through which the fuel can be ignited and through which the combustion products escape. The fuel in these pots is lit by applying a torch or the like near the surface of the fuel.

The filling and maintenance of heaters in an orchard requires a considerable amount of manual labor. Also, since at certain stages of bloom, a crop can be damaged if it is exposed to undesirably low temperature for as little as thirty minutes, the orchard must have on hand each night enough workmen to light all the heaters within a short interval. Further, to assure that the heaters will be lit in time, it is customary to start lighting them when the temperature has dropped to a point about two degrees above the critical temperature. If the temperature does not then drop to the critical temperature, the burned fuel has been wasted.

Various systems have been proposed for solving the orchard heater problem. The patents to Evans et al U.S. Pat. Nos. 1,493,070, Chapman et al 2,291,606,

Lea et al 2,286,366, Taylor 1,751,370, Van Tubergen 2,688,999 disclose various mechanisms and systems designed to overcome certain problems in this field. Also, systems are now being used wherein the fuel is piped through the orchard to the heaters which still must be'manually ignited.

BRIEF SUMMARY OF THE INVENTION In accordance with the present invention, a thermostat located in an orchard senses the dropping of the temperature and, at an appropriate time, opens a control valve in a liquid fuel supply line which is arranged to supply fuel to a burner in each heater. The pressure in the line actuates a pressure-sensitive switch to close contactsin an electric circuit that is energized by a series of dry cell batteries. The system also includes an ignition element that is connected in the circuit and is mounted in the wall of the heater to extend inwardly to a point adjacent the burner in the heater. Accordingly, as the fuel flows to each burner, the ignition element associated'with the burner is energized to effect ignition of the fuel. 1

Accordingly, it is an object of the invention to provide an improved mechanism for automatically igniting a series of orchard heaters.

Another object is to provide an improved igniter device. I

A further object is'-to provide an improved electric control circuit for an orchard heating system.

Other and further objectsand advantages will be apparent from the attached specification and drawings.

IN THE DRAWINGS FIG. 1 is a fragmentary, diagrammatic side elevation of an orchard heater system constructed in accordance with the present invention.

FIG. 2 is an enlarged central section taken through a portion of FIG. 1.

FIG. 3 is an enlarged fragmentary side elevation of a portion of FIG. 1, the view being taken inside the heater of FIG. I looking substantially in the direction of arrows 3-3 of FIG. 1.

FIG. 4 is a vertical section at reduced scale along line 4-4 of FIG. 3.

FIG. 5 is a section taken along line 5-5 of FIG. 3.

FIG. 6 is a section similar to FIG. 4 but showing parts in a different operating position.

FIG. 7 is an enlarged section taken along line 77 of I FIG. 6.

FIG. 8 is an enlarged section taken along line 8-8 of FIG. 6'.

FIG. 9 is an enlarged vertical section through one wall of a heater illustrating a second embodiment of the igniter of the present invention.

FIG. 10 is a view similar to FIG. 9 but showing the igniter in longitudinal section.

FIG. 11 is a section taken on line 11-1 1 of FIG. 10.

FIG. 12 is a fragmentary end elevation, the view being taken looking in the direction of arrows 12-12 of FIG. 10.

FIG. 13 is an end elevation of a third embodiment of the igniter of the present invention.

FIG. 14 is a section taken along line 14-14 of FIG. 13.

FIG. 15 is a section taken along line l5--15 of FIG. 14.

FIG. 16 is a vertical section through a heater wall, illustrating a fourth embodiment of the igniter of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 the reference numeral 25 indicates a conduit or line arranged to convey fuel oil from a supply tank 26 to a plurality of orchard heaters 27 (one only being shown). Suitable filters, gauges, and a pump are associated with the conduit in conventional manner to move oil from the tank to the heaters at a pressure of approximately psig.

A valve 30 which is connected in fuel line 25, is of the solenoid-operated type and is arranged to be opened and closed under the control of a thermostat 31 which is mounted in a suitable control box 32 supported on a post or the like that is located at a strategic position in the orchard. The arrangement is such that, when the temperature in the orchard lowers to a predetermined level, the thermostat will operate conventional electrical controls to actuate the valve 30 to open the fuel line and permit the associated pump to force fuel oil to each heater 27.

Each heater includes a sheet metal, frustoconical, perforated housing 27a that is open at its upper and lower ends and is arranged to rest on the ground. A section of the fuel line 25 extends through an opening in the sidewall of the housing and terminates in a nozzle 35 that is disposed substantially on the vertical axis of housing 27a and is arranged to emit the liquid fuel in a spray or atomized form and direct it upwardly in the housing.

An igniter 33 is mounted in the wall of housing 27a and comprises a stainless-steel tubular housing 34 (FIG. around which is welded a collar 36 having a flange 36a. The tubular housing is fitted through a circular opening in the wall of housing 270 with the flange 36a abutting the inner surface of the wall. A spring washer 38, which has an inner peripheral edge tightly gripping the housing 34, secures the housing to the wall 27. The igniter housing 34 has an opening 34a on the lower side of the portion of the housing that is outside the heater. A teflon bushing 37, which is secured in the end of the housing 34, slidably supports a conductor rod 39 that carries a triangularly-shaped metal clip 40 at one end and is fixed at its other end in a carrier block 41. The block 41 is of high heat resistant ceramic and is pressed into a stainless-steel tube 43 which is slidably mounted in housing 34 and is of generally square transverse cross section as seen in FIG. 8, the sides of the tube 43 and the internal wall of igniter housing 34 cooperating to define four longitudinal passages 44 leading through the wall of the heater. It will be noted in FIG. 5 that air may enter the igniter housing 34 through the lower opening 34a and pass along the passages 44 inwardly of the heater housing 27a to cool the air adjacent a platinum filament 46 which is mounted in a plug 47. The plug has a brass outer liner 47a which provides threads so that the plug can be removably secured in a tapped opening in a ceramic block 48 carried by tube 43. Any other suitable method of securing the filament 46 in the tube 43 may be used. One end of the filament 46 is insulated from the brass liner 47a of the plug 47 but is connected to a metal button 49 that is carried by the plug and is held in engagement with the end of conductor rod 39. The other end of filament 46 is connected to the brass liner 47a which engages an apertured metal disc 52 that is held against the end of the block 48 by a shoulder on the plug. The disc 52 also bears against the end of a second conductor rod 53 which is fixedly supported in the blocks 41 and 48.

A conductor wire 50 is secured to the end of the igniter housing 34 by means of a metal clip 51 that is fastened to the wire and has prongs 51a embedded in the bushing 37. When the triangular clip 40 is in face to face contact with the generally circular face of clip 51, a circuit is completed from a source of electric power through the wire 50, the clips 51 and 40, the conductor rod 39, button 49, filament 46, brass liner 47a, disc 52, conductor rod 53 and a wire 55 connected to rod 53. When this circuit is closed, the filament 46 is energized.

The circuit is opened to de-energize filament 46 by moving the triangular clip 40 to the position of FIG. 6. This movement is accomplished by a bi-metal actuator 60 (FIG. 4) that is welded at its upper end to a support strap 61 secured on the flange 36a of collar 36 and has, at its lower end, a tab 600 that is apertured to receive a pin 63 projecting upwardly from the tube 43, as best seen in FIG. 5. The bi-metal actuator 60 is so arranged that, when the bi-metal actuator is unheated, it holds the tube 43 and the filament 46 in the position of FIG. 4. When the actuator has been heated and reaches a certain temperature, as when the heater is in operation, the actuator moves toward the support strap 61 as shown in FIG. 6 and, in so moving, it slides the tube 43 and the conductor rod 39 to the left, moving the triangular clip 40 out of contact with the circular clip 51 to break the circuit to the filament 46. It will be noted that, during this circuit-breaking movement, the filament 46 is moved to a protected position within the housing 34, with the pin 63 traveling in a slot 64 (FIG. I

8) in housing 34.

Three conventioned dry-cell, 1.5 volt batteries (FIG. 1) are arranged in series and connected between the conductor wire 50 and a wire 71 that leads to a terminal 72 (FIG. 2) in a pressure-actuated switch 73 which includes a terminal 74 to which the conductor wire 55 is connected. The switch 73 includes a saddle 76 which is clamped around the fuel line 25. The saddle comprises a lower member 77 and an upper member 78, the two members being bolted together, with a passage 78a in the upper member in flow communication with a through-hole 79 in the wall of fuel line 25. The passage 78a leads into a pressure chamber 80 formed by an extemally-threaded tubular section 78b of the upper saddle member 78 and a cap 81 disposed on section 78b. A resilient flexible circular diaphragm 83 is disposed in chamber 80, having its peripheral edges sealed to the tubular section 78b and carrying an actuator pin 85 secured to and projecting upwardly from its upper surface. The pin, which is of nonconducting material, extends through a guide hole 86 in the cap 81 and abuts, at its upper end, a conductor bar 87 in the form of a flat spring that is connected at one end to contact 72 and is bent to normally assume a position wherein its end 87a is spaced from contact 74. It will be seen that, when pressurized liquid fuel flows through line 25, it will enter the chamber below the diaphragm 83 and force it and the bar 87 upwardly to engage bar 87 to close the circuit between contacts 72 and 74. When the flow of fuel in line 25 stops, the resilient bar 87 returns to its normal position with end 87a out of contact with contact 74 to open the circuit.

The operation of the system will be explained with reference to FIG. 1. When the temperature in the orchard drops to the point at which the heaters should be lit, the thermostat 31 actuates the valve 30 to open the fuel line 25 to permit liquid fuel at about psig. to flow toward the several heaters. The pressurized fuel actuates switch 73 to close contact 74 and thereby establish a circuit through the filament 46which at that time, has been projected by the cool bi-metal actuator 60 to its innermost position above and slightly laterally of the burner 35. When the filament is heated to a suitable point, the fuel issuing from the burner is ignited. As the temperature within the heater housing 27a is raised, the actuator withdraws the filament 46 into the igniter housing 34, moving the clip 40 away from the housing to break the circuit and de-energize the filament 46. If for some reason the burner is extinguished, the interior of the heater housing will cool off and the bi-metal actuator will project the filament inwardly, causing the clip 40 to close the circuit and again energize the filament to light the burner.

A second embodiment 33' of the igniter of the present invention is illustrated in FIGS. 9-12. In this embodiment a block 100 of ceramic or Teflon material is mounted by means of a bracket 101 to the exterior surface of a heater wall 27a which is identical to heater wall 270 (FIG. 1). A conductor rod 103 is locked in the block by a short pin 104, and has an end portion 103a projecting from the block to receive a connector 105 that electrically connects the rod to a wire 50' which leads to the dry cell batteries in the same manner that the wire 50 of FIG. 1 is connected to the batteries. At its other end, the conductor rod 103 has a reduced diameter section l03b locked in a ceramic block by a pin 111. The end of section 1113b has an opening 1103c in which a brass socket 113 is snugly received. One end of a filament 115 is secured to the socket 113 while the other end is secured to a similar brass socket 116 which is tightly fitted into an axial opening 118a in a short conductor rod 118. The rod 118 is held in the ceramic block 110 by a nut 119 that is in threaded engagement with the end of the rod 118. An enlarged head portion 11% is slotted to receive the end of a bimetal member 120 which is secured in the slot by nickel silver solder. The free end of the bi-metal member 120 travels in a recess 122 in the block 100 and carries a contact point 123 that is arranged to be moved into engagement with the inner wall of a copper ring 125 mounted on the block 100, when the bi-metal member 120 is cool. The copper ring is also in contact with a conductor rod 126 that receives a connector 127 which electrically connects the rod 126 to a wire 55' which leads to the pressure switch 73 in the manner that wire 55 (FIG. 1) leads to the switch.

It will be noted that the opening 130 (FIG. 10) in the heater wall 27a permits air currents to cool the filament 1 15. r

The operation of the igniter 33' of FIGS. 9-12 is similar to the operation of igniter 33 of FIGS. 1-8 in that, when the thermostatically-operated valve 30 in the fuel line 25 is opened, causing closure of the circuit contacts in the pressure switch 73, the battery-energized circuit' is completed and the filament 115 is energized to ignite the fuel being emitted from the burner 35. When the bi-metal element 120 reaches a predetermined temperature, it swings to the phantom line position of FIG. 10 to open the circuit and de-energize the filament. If the burner is extinguished, the cooling of the interior of the housing causes the bi-metal element to swing to the full line position of FIG. 10 to re-make the circuit, energize the filament, and re-light the burner.

A third embodiment 33" of the igniter of the present invention is shown in FIGS. 13-15. In this arrangement, an elongated rectangular plate (FIG. 13) lies flat against the outer surface of a heater wall 27a", being secured as its lower end to the wall by a screw 136 (FIG. 14) and having near its upper end a circular hole 135a defined'by an inturned flange 135b that fits snugly in a flanged opening in the wall 27a". A filament 140 is mounted in the ends of two adjacent metal rods 141 and 142 which are fixedly secured in a ceramic block 144 that is secured to the outer surface of plate 135 by two spring clips 145 and 146. The rod 141 is connected to a wire 50" that leads to the dry cell batteries in the manner of wire 50 of FIG. 1. A brass leaf spring 148 is secured to the block 144 by a screw 149 in electrical contact with a wire 55" leading to the pressure switch 73 in the manner of wire 55 (FIG. 1). The leaf spring 148 is normally biased into contact with the end of rod 142 so that, when the solenoid-actuated valve has opened the fuel line and pressurized fuel has actuated the switch 73 to close the contacts therein, a circuit is closed through wire 50", rod 141, filament 140, rod 142, brass leaf spring 148 and wire 55".

A bi-metal element 150 is secured at its lower end to plate 135 by the screw 136. When cool the element normally lies in an elongated opening 151 in plate 135 in flush contact with the outer wall 27a" of the heater housing as shown in phantom lines in FIG. 14. When the filament 140 has been energized and the burner has been lighted, the wall 27a" becomes heated and this heat is transferred directly to the bi-metal element 150, causing it to move' to the full line position of FIG. 14. During this movement, a bent upper end 150a of the element 150 engages the brass leaf spring 148 and moves it out of contact with the rod 142 to open the circuit and de-energize the filament 140.

In FIG. 16 a fourth embodiment 33" of the igniter of the present invention is illustrated. In this form, a metal tubular housing is locked in the wall 27" of a heater by two lock nuts 161 which engage a threaded end portion 162 of the housing. The threaded end portion has a slot 162a extending for about 90 of the periphery of the tubular end to provide a flow passage for cooling air entering the heater and passing over a filament 163. A grommet 165 of insulating material such as rubber insulates the housing 160 and the nuts 161 from the heater wall. Three conductor rods 170, 171 and 172 are fixedly mounted in a block 174 of insulating material, such as Teflon, that is fixed in the housing. The rod is arranged to receive a connector 175 that electrically connects the rod to a wire 50" which leads to the dry cell batteries in the same manner that the wire 50 of FIG. 1 is connected to the batteries. The rod 172 is in contact with the internal surface of metal housing 160 and is arranged to receive a connector 176 that electrically connects the rod to a wire 55" which leads to the pressure switch 73 in the manner that wire 55 (FIG. 1) leads to the switch. The filament 163 is connected between the inner ends of the rods 170 and 171, the rod 171 also acting as a support for a bi-metal element 180 which is fastened at one end to rod 171 and at the other end carries a contact point 181 that is adapted to contact the inner wall of housing 160.

The operation of the ignitor 33" of FIG. 16 is similar to the operation of igniter 33 of FIGS. 1-8 in that, when the thermostatically-operated valve 30 in the lineis opened, causing closure of the circuit contacts in the pressure switch 73, the battery-energized circuit is completed and the filament 163 is energized to ignite the fuel being emitted from the burner 35. When the bi-metal element 180 reaches a predetermined temperature, the contact 181 moves out of engagement with the housing 160 to open the circuit and de-energize the filament. When the burner is extinguished and the interior of the heater cools down, the bi-metal element moves the contact 181 back to its position against the housing wall.

In all of the igniters of FIGS. 9 16 the bi-metallic elements are in the flame of the ignited fuel for fast heating, thus de-energizing the igniter-battery circuit quickly to reduce battery drain. In orchard heaters the fuel is continually delivered to each heater whether it is ignited or not. If the flame goes out, it is desirable to relight the fuel as soon as possible to avoid the formation of a puddle of fuel in or under the heater that when ignited may cause carboning of the fuel nozzle. Thus all of the igniters of FIGS. 9 16 are positioned as shown in dotted lines in FIG. 1 in the path of the cool fuel emitted from the atomizing nozzles for rapid cooling of the bi-metallic element, thus re-energizing the igniterbattery circuit quickly after an inadvertent loss of the flame in the heater to reduce accumulations of fuel in the heater housing.

The several embodiments of the ignition system described above make use of a liquid fuel supply. It is within the scope of the present invention to employ a gaseous fuel under pressure with the disclosed apparatus.

From the foregoing description it will be apparent that the present invention provides an improved orchard heating system designed to provide the automatic, reliable ignition of heaters in an orchard. The use of a thermostat to effect the lighting of the burners in the heaters through a fuel line pressure switch combines the sensitive action of a thermostat and the reliable positive action of a pressure-actuated switch to effect ignition of the heaters.

lt will be understood that modifications and variations may be effected without departing from the scope of the present invention which is limited only by the scope and proper interpretation of the appended claims.

I claim:

1. In an orchard heating system, an orchard heater adapted to be positioned in a remote location in a field having a housing and a burner in the housing, means for delivering liquid fuel to the burner of said heater, ignition means having an igniting element adjacent said burner, means for energizing said element to ignite fuel issuing from said burner, said energizing means including battery means and an electric circuit coupling the battery means with said igniting element, and control means having heat sensing means in the flame of the ignited fuel and responsive to the elevation of temperature within the heater housing to a predetermined value to de-energize said circuit to said element and in the path of the fuel sprayed into the housing so that cool fuel will rapidly cool the heat sensing means to re-energize the ignition element so that a flame is reestablished as soon as possible to prevent an undue accumulation of fuel in the housing, said control means having a pair of contacts coupled to said circuit wherein said circuit is de-energized by movement of one of said contacts, said heat sensing means including linkage means for moving said one contact responsive to a temperature rise sensed by said heat sensing means, said contacts being positioned externally of said housing so as to remain free of soot formed within the housing.

2. In an orchard heating system, an orchard heater adapted to be positioned in a remote location in a field having a housing and a burner in the housing, means for delivering fuel to the burner of said heater, ignition means having an igniting element adjacent said burner, means for energizing said element to ignite fuel issuing from said burner, said energizing means including battery means and an electric circuit coupling the battery means with said igniting element, and control means having heat sensing means in the flame of the ignited fuel and responsive to the elevation of temperature within the heater housing to a predetermined value to de-energize said circuit to said element, said control means having a pair of contacts coupled to said circuit wherein said circuit is de-energized by movement of one of said contacts, said heat sensing means including linkage means for moving said one contact responsive to a temperature rise sensed by said heat sensing means, said contacts being positioned externally of said housing so as to remain free of soot formed within the housing and wherein said heat sensing means includes an elongated bi-metal element mounted at a first end on said housing and at a second end to said ignition element, said second end of said bi-metal element being movable upon heating toward said housing for moving said element away from a position adjacent said burner and being movable upon cooling toward said burner for moving said element to a position adjacent said burner.

3. The combination of claim 1 wherein said ignition means includes a support for said igniter element removably secured to said housing.

4. The combination of claim 1 wherein said housing has an opening in one wall and said ignition means includes an igniter-element support means removably secured to the exterior of said wall and projecting through the opening to position said element in operative relation to the burner in said housing.

5. An orchard heating system comprising a plurality of orchard heaters adapted to rest in a remote field, each heater having a housing and a burner within the housing, a common liquid fuel supply conduit adapted to deliver fuel under pressure to the burner in each heater, an ignition device having an igniting element adjacent each said burner, means for electrically energizing said element, said energizing means including battery means at each heater, an electrical circuit energizable to couple said battery means to said igniting element, means responsive to the pressure in said fuel conduit for activating said energizing means to energize said element for effecting the ignition of fuel issuing from said burner, and control means for said electrical circuit including a heat sensitive element positioned in the flame of the burner for de-energizing said electrical circuit upon sensing the flame temperature and in the path of the fuel sprayed into the housing so that cool fuel will rapidly cool the heat sensing means to re-energize the ignition element so that a flame is reestablished as soon as possible to prevent an undue accumulation of fuel in the housing.

6. A system according to claim 5 wherein said ignition device is a high resistance element capable of being heated to a temperature sufficient to cause ignition of the fuel emitted from said burner.

7. A system according to claim 5 wherein said pressure responsive means is a switch having contacts in said circuit arranged to be closed by pressure in said supply conduit.

8. An orchard heating system comprising a plurality of orchard heaters adapted to rest in a remote field, each heater having a housing and a burner within the housing, a common fuel supply conduit adapted to deliver fuel under pressure to the burner in each heater, an ignition device having an igniting element adjacent each said burner, means for electrically energizing said element, said energizing means including battery means at each-heater, an electrical circuit energizable to couple said battery means to said igniting element, means responsive to the pressure in said fuel conduit. for activating said energizing means to energize said element for effecting the ignition of fuel issuing from said burner, and control means for said electrical circuit including a heat sensitive element positioned in the flame of the burner for de-energizing said electrical circuit upon sensing the flame temperature, said heat sensitive element including a bi-metal support member arranged to move said igniting element to a position adjacent said burner when said support member is at a first temperature and to move said element to a position remote from said burner when said bi-metal support member reaches a temperature that is a predetermined number of degrees above said first temperature.

9. An orchard heating system according to claim including a valve in said fuel supply conduit, a thermostat responsive to temperature in the orchard and operatively connected to said valve to open said valve at a predetermined orchard temperature to activate said pressure-responsive member for energizing said igniting element.

10. In an'orchard heating system, an orchard heater adapted to be positioned in a remote location in a field having a housing and a burner in the housing, means for delivering fuel to the burner of said heater, ignition means having an igniting element adjacent said burner, means for energizing said element to ignite fuel issuing from said burner, said energizing means including battery means and an electric circuit coupling the battery means with said igniting element, and control means having heatsensing means in the flame of the ignited fuel and responsive to the elevation of temperature within the heater housing to a predetermined value to de-energize said circuit to said element, said control means having a pair of contacts coupled to said circuit wherein said circuit is de-energized by movement of one of said contacts, said heat sensing means including linkage means for moving said one contact responsive to a temperature rise sensed by said heat sensing means, said contacts being positioned externally of said housing so as to remain free of soot formed within the housing, wherein said housing has an opening in one wall and said ignition means includes an igniter-element support means removably secured to the exterior of said wall and projecting through the opening to position said element in operative relation to the burner in said housing and wherein said support means provides a passage for air entering said housing in the vicinity of said igniting element.

11. The combination of claim 5 said electrical circuit including electrical contacts positioned externally of the housing thus out of the path of the products of combustion of the fuel and being operatively coupled to said heat sensitive element for opening and closing the contacts responsive to temperature changes sensed b said heat sensitive element.

12. In an orchard heating system, a heater having a housing and a burner in the housing, means for delivering fuel to the burner of said heater, ignition means having an igniting element adjacent said burner, means for energizing said element to ignite fuel issuing from said burner, and control means responsive to the elevation of temperature within the heater housing to a predetermined value to de-energize said element, said ignition means comprising a guide housing mounted in and extending through an opening in a well of said heater housing, electric circuit contacts mounted on the outer end of said guide housing exteriorly of said wall, a conductor mounted in said guide housing for movement longitudinally thereof and having a first end portion adjacent the outer end portion of said guide housing and a second end portion disposed adjacent the inner end of the guide housing inside said heater housing, contact points mounted on said first end portion of said conductor, said igniting element being mounted on said second end portion of said conductor, and said control means comprising a temperatureresponsive member mounted on said heater housing interiorly thereof and connected to said conductor for moving said conductor between an igniting position wherein said igniting element is adjacent said burner and conductor contact points are in engagement with said electric circuit contacts to partially complete a circuit through said igniting element, and a second position wherein said points are out of contact with said electric circuit contacts and said igniting element is spaced further from said burner.

13. In an orchard heating system, a heater having a housing and a burner in the housing, means for delivering fuel to the burner of said heater, ignition means having an igniting element adjacent said burner, means for energizing said element to ignite fuel issuing from said burner, and control means responsive to the elevation of temperature within the heater housing to a predetermined value to deenergize said element, said ignition means comprising a support member mounted on an exterior wall of said heater housing adjacent an opening therein, a fixed electrical contact on said support member, an electrical conductor mounted on said support member and extending through said opening and having an end portion supporting said igniting element adjacent said burner, said conductor and said fixed contact being in the electrical energizing circuit of said igniting element, said control means comprising a temperature-responsive member of electrically conductive material connected in said circuit and anchored at one end internally of said heater housing and having a contact movable into engagement with said fixed contact of said support member to close said circuit and energize said igniting element when said member is at a predetermined temperature and movable out of engagement with said contact when said member is heated to a temperature above said predetermined temperature.

14. In an orchard heating system, a heater having a housing and a burner in the housing, means for delivering fuel to the burner of said heater, ignition means having an igniting element adjacent said burner, means for energizing said element to ignite fuel issuing from said burner, and control means responsive to the elevation of temperature within the heater housing to a predetermined value to deenergize said element, said ignition means comprising a support member mounted on an exterior wall of said heater housing adjacent an opening therein, an electrical conductor mounted on said support member and having an end portion supporting said igniting element adjacent said burner, a

being anchored to said wall and the other end being free and movable outwardly away from said wall in response to a rise in temperature of said member when said wall is heated, said contactor having a portion disposed in the path of movement of the movable end of said member to be contacted thereby and moved out of contact with said conductor incident to outward movement of said free end of said member.

* I! l 1' F 

1. In an orchard heating system, an orchard heater adapted to be positioned in a remote location in a field having a housing and a burner in the housing, means for delivering liquid fuel to the burner of said heater, ignition means having an igniting element adjacent said burner, means for energizing said element to ignite fuel issuing from said burner, said energizing means including battery means and an electric circuit coupling the battery means with said igniting element, and control means having heat sensing means in the flame of the ignited fuel and responsive to the elevation of temperature within the heater housing to a predetermined value to de-energize said circuit to said element and in the path of the fuel sprayed into the housing so that cool fuel will rapidly cool the heat sensing means to re-energize the ignition element so that a flame is re-established as soon as possible to prevent an undue accumulation of fuel in the housing, said control means having a pair of contacts coupled to said circuit wherein said circuit is de-energized by movement of one of said contacts, said heat sensing means including linkage means for moving said one contact responsive to a temperature rise sensed by said heat sensing means, said contacts being positioned externally of said housing so as to remain free of soot formed within the housing.
 2. In an orchard heating system, an orcharD heater adapted to be positioned in a remote location in a field having a housing and a burner in the housing, means for delivering fuel to the burner of said heater, ignition means having an igniting element adjacent said burner, means for energizing said element to ignite fuel issuing from said burner, said energizing means including battery means and an electric circuit coupling the battery means with said igniting element, and control means having heat sensing means in the flame of the ignited fuel and responsive to the elevation of temperature within the heater housing to a predetermined value to de-energize said circuit to said element, said control means having a pair of contacts coupled to said circuit wherein said circuit is de-energized by movement of one of said contacts, said heat sensing means including linkage means for moving said one contact responsive to a temperature rise sensed by said heat sensing means, said contacts being positioned externally of said housing so as to remain free of soot formed within the housing and wherein said heat sensing means includes an elongated bi-metal element mounted at a first end on said housing and at a second end to said ignition element, said second end of said bi-metal element being movable upon heating toward said housing for moving said element away from a position adjacent said burner and being movable upon cooling toward said burner for moving said element to a position adjacent said burner.
 3. The combination of claim 1 wherein said ignition means includes a support for said igniter element removably secured to said housing.
 4. The combination of claim 1 wherein said housing has an opening in one wall and said ignition means includes an igniter-element support means removably secured to the exterior of said wall and projecting through the opening to position said element in operative relation to the burner in said housing.
 5. An orchard heating system comprising a plurality of orchard heaters adapted to rest in a remote field, each heater having a housing and a burner within the housing, a common liquid fuel supply conduit adapted to deliver fuel under pressure to the burner in each heater, an ignition device having an igniting element adjacent each said burner, means for electrically energizing said element, said energizing means including battery means at each heater, an electrical circuit energizable to couple said battery means to said igniting element, means responsive to the pressure in said fuel conduit for activating said energizing means to energize said element for effecting the ignition of fuel issuing from said burner, and control means for said electrical circuit including a heat sensitive element positioned in the flame of the burner for de-energizing said electrical circuit upon sensing the flame temperature and in the path of the fuel sprayed into the housing so that cool fuel will rapidly cool the heat sensing means to re-energize the ignition element so that a flame is re-established as soon as possible to prevent an undue accumulation of fuel in the housing.
 6. A system according to claim 5 wherein said ignition device is a high resistance element capable of being heated to a temperature sufficient to cause ignition of the fuel emitted from said burner.
 7. A system according to claim 5 wherein said pressure responsive means is a switch having contacts in said circuit arranged to be closed by pressure in said supply conduit.
 8. An orchard heating system comprising a plurality of orchard heaters adapted to rest in a remote field, each heater having a housing and a burner within the housing, a common fuel supply conduit adapted to deliver fuel under pressure to the burner in each heater, an ignition device having an igniting element adjacent each said burner, means for electrically energizing said element, said energizing means including battery means at each heater, an electrical circuit energizable to couple said battery means to said igniting element, means responsive to the pressure in said fuel conduit for activating said energizing means to energize said element for effecting the ignition of fuel issuing from said burner, and control means for said electrical circuit including a heat sensitive element positioned in the flame of the burner for de-energizing said electrical circuit upon sensing the flame temperature, said heat sensitive element including a bi-metal support member arranged to move said igniting element to a position adjacent said burner when said support member is at a first temperature and to move said element to a position remote from said burner when said bi-metal support member reaches a temperature that is a predetermined number of degrees above said first temperature.
 9. An orchard heating system according to claim 5 including a valve in said fuel supply conduit, a thermostat responsive to temperature in the orchard and operatively connected to said valve to open said valve at a predetermined orchard temperature to activate said pressure-responsive member for energizing said igniting element.
 10. In an orchard heating system, an orchard heater adapted to be positioned in a remote location in a field having a housing and a burner in the housing, means for delivering fuel to the burner of said heater, ignition means having an igniting element adjacent said burner, means for energizing said element to ignite fuel issuing from said burner, said energizing means including battery means and an electric circuit coupling the battery means with said igniting element, and control means having heat sensing means in the flame of the ignited fuel and responsive to the elevation of temperature within the heater housing to a predetermined value to de-energize said circuit to said element, said control means having a pair of contacts coupled to said circuit wherein said circuit is de-energized by movement of one of said contacts, said heat sensing means including linkage means for moving said one contact responsive to a temperature rise sensed by said heat sensing means, said contacts being positioned externally of said housing so as to remain free of soot formed within the housing, wherein said housing has an opening in one wall and said ignition means includes an igniter-element support means removably secured to the exterior of said wall and projecting through the opening to position said element in operative relation to the burner in said housing and wherein said support means provides a passage for air entering said housing in the vicinity of said igniting element.
 11. The combination of claim 5 said electrical circuit including electrical contacts positioned externally of the housing thus out of the path of the products of combustion of the fuel and being operatively coupled to said heat sensitive element for opening and closing the contacts responsive to temperature changes sensed by said heat sensitive element.
 12. In an orchard heating system, a heater having a housing and a burner in the housing, means for delivering fuel to the burner of said heater, ignition means having an igniting element adjacent said burner, means for energizing said element to ignite fuel issuing from said burner, and control means responsive to the elevation of temperature within the heater housing to a predetermined value to de-energize said element, said ignition means comprising a guide housing mounted in and extending through an opening in a well of said heater housing, electric circuit contacts mounted on the outer end of said guide housing exteriorly of said wall, a conductor mounted in said guide housing for movement longitudinally thereof and having a first end portion adjacent the outer end portion of said guide housing and a second end portion disposed adjacent the inner end of the guide housing inside said heater housing, contact points mounted on said first end portion of said conductor, said igniting element being mounted on said second end portion of said conductor, and said control means comprising a temperature-responsive member mounted on said heater housing interiorly thereof and connected to said conductor for moving said conductor between an igniting position wherein said igniting element is adjacent said burner and conductor contact points are in engagement with said electric circuit contacts to partially complete a circuit through said igniting element, and a second position wherein said points are out of contact with said electric circuit contacts and said igniting element is spaced further from said burner.
 13. In an orchard heating system, a heater having a housing and a burner in the housing, means for delivering fuel to the burner of said heater, ignition means having an igniting element adjacent said burner, means for energizing said element to ignite fuel issuing from said burner, and control means responsive to the elevation of temperature within the heater housing to a predetermined value to deenergize said element, said ignition means comprising a support member mounted on an exterior wall of said heater housing adjacent an opening therein, a fixed electrical contact on said support member, an electrical conductor mounted on said support member and extending through said opening and having an end portion supporting said igniting element adjacent said burner, said conductor and said fixed contact being in the electrical energizing circuit of said igniting element, said control means comprising a temperature-responsive member of electrically conductive material connected in said circuit and anchored at one end internally of said heater housing and having a contact movable into engagement with said fixed contact of said support member to close said circuit and energize said igniting element when said member is at a predetermined temperature and movable out of engagement with said contact when said member is heated to a temperature above said predetermined temperature.
 14. In an orchard heating system, a heater having a housing and a burner in the housing, means for delivering fuel to the burner of said heater, ignition means having an igniting element adjacent said burner, means for energizing said element to ignite fuel issuing from said burner, and control means responsive to the elevation of temperature within the heater housing to a predetermined value to deenergize said element, said ignition means comprising a support member mounted on an exterior wall of said heater housing adjacent an opening therein, an electrical conductor mounted on said support member and having an end portion supporting said igniting element adjacent said burner, a movable contactor mounted on said housing and biased into contact with one end of said conductor, said conductor and said contactor being connected in the electrical energizing circuit of said igniting element, said control means comprising a temperature-responsive member mounted on the exterior wall of said heater housing and arranged to lie in substantially flat heat-transfer relation with said wall when said member is at a predetermined temperature, one end of said member being anchored to said wall and the other end being free and movable outwardly away from said wall in response to a rise in temperature of said member when said wall is heated, said contactor having a portion disposed in the path of movement of the movable end of said member to be contacted thereby and moved out of contact with said conductor incident to outward movement of said free end of said member. 